Local structure of europium and iron sites in zinc borate glasses

Samples of zinc borate glasses, doped with europium or iron ions, were prepared and examined by 151Eu and 57Fe Mössbauer spectroscopy. The structural features of the rare earth and transition metal ion sites have been investigated with particular attention to the coordination number, distortion and degree of disorder. The relative concentrations of the different oxidation states have been also determined. The disorder of the sites was investigated by using the convolution method for the analysis of the spectra of glasses. The resulting distibution of the quadrupole interaction parameter is due to the structural disorder of the dopant ion sites and its standard deviation gives an evaluation of the degree of disorder. The results for zinc borate glasses are compared with the ones found for iron doped phosphate glasses and europium metaphosphate glass